Not applicable.
Not applicable
1. Field of the Invention
Motorized rollers (i.e. a roller with an internal motor) are common in the conveyor industry. Motorized rollers are not common in treadmills, which use an external motor to drive the roller.
2. Description of the Related Art
Present state-of-the-art in conveyor design uses an internal motor assembled in the conveyor roller tube. The internal motor drives gears and clutches that provide power to convey heavy loads. The requirement for gears and clutches makes this design relatively expensive.
The motorized rollers presently used by conveyors are not suited to treadmills because treadmills are very sensitive to cost, have extreme foot impact loads, require variable speeds, and have greater duty cycles. A 200 pound treadmill runner at 10 M.P.H. will have an inertia impact of three to four times his weight or about 700 pounds of localized foot impact on a moving belt above a non-moving deck at an approximate rate of one hundred (100) times a minute. Treadmills must support higher speeds and a more resilient drive coupled with lower costs than provided by current conveyer motorized rollers. Therefore, treadmills use belt drives which are quiet, absorb shock, cost effective, easy maintenance/assembly and more efficient through less loss of friction compared to gears. However, in order to implement these belt drives, it has been necessary up to now to mount drive motors externally on the front of the treadmill under a shroud. This increases profile of the treadmill (creating a front bulge that runners have to be careful to avoid) and also enlarges its footprint, wasting expensive gym floor space (see FIG. 4). Internal clutches are also required to prevent damage in case of sudden shock loads. Lastly, it is difficult to maintain belt tension because front roller drives pushes the runner on the belt rather than pulling said runner.
An in-depth search for treadmills revealed only one patent for treadmills that has a motor inside the roller (U.S. Pat. No. 5,509,872). In this patent, there are two motors and gears (not a belt drive). All production treadmill belt drives have the motor external (ref. U.S. Pat. No. 5,509,872 xe2x80x9cPriorArtxe2x80x9d). The two-motor device in U.S. Pat. No. 5,509,872 device does not appear to be in production.
This invention is a rear roller drive assembly that can be used either for treadmills or conveyor systems. An all-belt drive provides the shock absorption required in the heavy impact, high friction duty cycle required for treadmills. Any suitable electric motor may be suspended as a purchased entity and integrated inside a tube as a modular package coupled with a two stage all belt drive system. Suitable clearance between the inner tube walls and the suspended motor is maintained by the motor drive shaft, bearings and shafting affixed to the rear motor housing (see FIG. 1). A belt drive FIGS. 1 and 2, absorbs shock loads. No clutches required. The resiliency of a belt drive ensures quiet operation even when coupled with high motor speeds. The two-stage reduction in FIG. 1, provides for a wide range of torque transmission. The non-rotating support shaft of the running belt drive roller is locked to the frame with a centering bracket such as a xe2x80x9cVxe2x80x9d shaped groove which in effect holds the shaft in position longitudinally as well as radially (see FIG. 3) This rigid horizontal bracket supports the suspended motor; prevents motor shaft from rotating and permits one bearing to support one end of the housing of the motor without putting a load on the motor assembly.
Space saved by an internal motor suspended in the treadmill rear drive roller provides a means to pull rather than push treadmill walking or running belt. Pushing a belt requires higher belt tensions (to prevent slipping) which in turn results in subsequently higher bearing radial loading.
Opposite clutch coupling and complete commercial motor entity facilitates motor removal and maintenance. All the efficiency, performance, and advantages in this belt drive are applicable in motorized rollers for powered conveyor systems.